The prior art provides various types of circular saw blades for cutting materials such as steel, concrete, asphalt and the like. In order to properly cut materials, most of these prior art saw blades must be rotated in a particular direction of rotation. More particularly, the cutting edge or teeth are generally oriented or angled such that the saw blades are capable of cutting in only one direction of rotation. Many times, the angle or orientation of the cutting edge or teeth is slight or non-existent, so it is sometimes not possible to determine the proper direction of rotation by visually inspecting the saw blade. With respect to many prior art saw blades, if the saw blades are rotated in the wrong or opposite direction during the cutting operation, the cutting edge or teeth of the saw blades can be permanently damaged.
In order to avoid rotating circular saw blades in the wrong direction, some prior art blades have included various types of visual indicators that serve to inform the user of the proper direction of rotation. One category of visual indicators commonly utilized are labels placed on the lateral surfaces of the saw blades. Additionally, some prior art saw blades have included markings or arrows that are stamped directly onto the lateral edges of the saw blade. Unfortunately, during cutting operations such labels and markings can be worn away. Thus, when a user proceeds to mount a saw blade on a drive unit wherein such markings are worn away, there is a possibility that the user will improperly mount the saw blade on the drive unit resulting in the saw blade being rotated in the wrong direction, thereby leading to the possibility of damaging the cutting edge of the saw blade when a user attempts to cut material with the improperly mounted saw blade.
The prior art further provides circular saw blades with circular openings in the lateral edges of the blade which serve to generate air flow and cool the cutting edge of the blade. These circular openings are located intermediate the axis of rotation and the cutting edge of the saw blade. In other prior art circular saw blades, openings are provided in the lateral edges of the blade that extend and open from the cutting edge of the blade radially inward towards the axis of rotation. These openings are also designed to provide cooling for the circular saw blade.